Three-dimensional graphene composite vapor chamber, preparation method and application thereof

Abstract

The application discloses a three-dimensional graphene composite heat plate, a preparation method and application thereof. The three-dimensional graphene composite heat plate comprises a base body and three-dimensional graphene in the base body. The three-dimensional graphene has a plurality of micro-pores which are interconnected, and the micro-pores contain moisture. The three-dimensional graphene composite heat plate has no limitation on the thickness, and can still have excellent heat equalizing capacity when the thickness is less than 400 microns. The processing difficulty is not affected by the thickness. In addition, the three-dimensional graphene composite heat plate can also have the heat radiation effect of graphene, and the heat dissipation capacity is further superior to that of a conventional heat plate. The prepared three-dimensional graphene has high density and interconnected micro-pores, and is more suitable for heat management application.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive composite materials technology, and in particular to a three-dimensional graphene composite heat exchanger, its preparation method and application. Background Technology

[0002] With the development of chips, they are becoming increasingly miniaturized and small-sized. Moreover, as chips operate at faster speeds and higher power, the problem of chip heat generation is becoming more and more serious. Conventional chip heat dissipation mainly uses a combination of high thermal conductivity synthetic graphite film and ultra-thin heat sink.

[0003] The vapor chamber is primarily made of copper or aluminum. Its main structure consists of two tightly sealed copper or aluminum caps at the top and bottom, supported by metal pillars of the same material. The internal structure is fabricated using etching, metal powder sintering, or metal mesh processes, and depressurized water is used as the working fluid. During operation, when one end of the vapor chamber is at a higher temperature, the internal water rapidly vaporizes, using a phase change to lower the temperature. The vaporized water then flows to the cold end, liquefies, and releases heat, quickly and evenly distributing the heat to prevent localized overheating and facilitate rapid heat conduction.

[0004] However, due to the limitations of the vapor chamber manufacturing process, its thickness is usually higher than 400 micrometers. If the vapor chamber is too thin, the internal working liquid capacity is insufficient, resulting in relatively poor heat dissipation. Currently, the thinnest vapor chamber is manufactured using an etching process, with a thickness of about 300 micrometers. The manufacturing process is complex, the cost is relatively high, and the heat dissipation effect is also relatively poor. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a three-dimensional graphene composite heat spreader, its preparation method, and its applications.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] In a first aspect, the present invention provides a three-dimensional graphene composite heat spreader, comprising: a matrix and three-dimensional graphene sealed within the matrix.

[0008] The three-dimensional graphene has multiple interconnected micropores, and the micropores contain water.

[0009] Secondly, the present invention also provides a method for manufacturing a three-dimensional graphene composite heat exchanger, comprising:

[0010] Three-dimensional graphene is provided, wherein the three-dimensional graphene has multiple interconnected micropores;

[0011] The three-dimensional graphene is sealed and encapsulated in a plate-shaped substrate to form a three-dimensional graphene composite heat sink.

[0012] The three-dimensional graphene itself contains moisture in its micropores, or the manufacturing method further includes a step of applying moisture to the three-dimensional graphene before sealing and encapsulation.

[0013] Thirdly, the present invention also provides the application of the above-mentioned three-dimensional graphene composite heat sink in the field of heat dissipation of electronic products.

[0014] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least the following:

[0015] The heat dissipation capacity of the three-dimensional graphene composite heat dissipation plate provided by the present invention is not limited by thickness. It can still maintain excellent heat dissipation capacity at different thicknesses, especially at thicknesses below 400μm, and the ease of processing is also not affected by thickness. In addition, the three-dimensional graphene composite heat dissipation plate provided by the present invention can also exert the thermal radiation effect of graphene, and its heat dissipation capacity is further superior to that of conventional heat dissipation plates.

[0016] The method for preparing a three-dimensional graphene composite heat spreader provided by this invention produces three-dimensional graphene with high density and interconnected micropores. The higher density and denser graphene growth make it more suitable for thermal management applications.

[0017] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below in conjunction with detailed drawings. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of a method for manufacturing a three-dimensional graphene composite heat spreader provided in a typical embodiment of the present invention.

[0019] Figure 2 This is a schematic flowchart of a method for preparing three-dimensional graphene provided in a typical embodiment of the present invention;

[0020] Figure 3a This is an electron microscope image of graphene grown by vapor phase epitaxy on the inner surface of a metal network motherboard, provided in a typical embodiment of the present invention.

[0021] Figure 3b This is an electron microscope image of three-dimensional graphene after the removal of the three-dimensional metal framework, provided in a typical embodiment of the present invention;

[0022] Figure 4a This is a schematic diagram of a heat dissipation capacity testing device for a heat spreader provided in a typical test case of the present invention.

[0023] Figure 4bThis is a schematic diagram from another perspective of the heat dissipation capacity testing device of the heat sink provided in a typical test case of the present invention.

[0024] Figure 5 This is an equilibrium temperature test diagram provided in a typical test case of the present invention. Detailed Implementation

[0025] The main problems with existing copper-based or aluminum-based heat spreaders include: 1) Complex manufacturing process, usually requiring etching, resulting in high cost; 2) Limited thickness due to process limitations, leading to relatively high space occupancy; 3) Heat spreaders conduct heat through the phase change of water, but copper itself has poor heat dissipation capacity, resulting in suboptimal cooling effect; 4) Temperature limitations, currently heat spreaders are generally used at temperatures not exceeding 75℃. Excessive temperature will cause copper to oxidize, and exceeding the phase change temperature of water will worsen the effect.

[0026] Therefore, in view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0028] Moreover, relational terms such as “first” and “second” are used merely to distinguish one component or method step from another that has the same name, and do not necessarily require or imply any such actual relationship or order between these components or method steps.

[0029] This invention provides a three-dimensional graphene composite heat spreader, comprising: a substrate and three-dimensional graphene sealed within the substrate; the three-dimensional graphene has a plurality of interconnected microchannels, and the microchannels contain moisture.

[0030] In some embodiments, the surface water content in the three-dimensional graphene is 5-10%.

[0031] The surface water content refers to the mass fraction of water in the surface layer of the three-dimensional graphene. Since most of the water can only be adsorbed in the micropores on the surface of the three-dimensional graphene before the matrix is ​​assembled into a whole, and it is difficult to retain it in the interior of the graphene, the present invention focuses on its surface water content. The surface water content is characterized by, for example, the weighing method. Specifically, the weight of the completely dried three-dimensional graphene is measured, and then the weight of the three-dimensional graphene with water content on the surface is measured after cleaning and freeze-drying. The water content is thus measured. Through repeated tests, an appropriate water content range of 5-10% is obtained.

[0032] In some more preferred embodiments, the microchannels may include, for example, multiple main channels and secondary channels; the multiple main channels are interconnected to form a main channel network; the multiple secondary channels are at least connected to adjacent main channels; the main channel network extends through both opposite sides of the three-dimensional graphene.

[0033] This preferred embodiment corresponds to the following embodiment of preparing three-dimensional graphene through high-density sponge, wherein the main channels are usually associated with the organic sponge skeleton of the high-density sponge, and the secondary channels are usually associated with the micro-channels formed when the hydrated precursors rapidly lose water. This combination of main and secondary channels can more fully expand the degree of channel connectivity and channel density, providing more space for water diffusion and phase change, thereby further improving the heat dissipation performance.

[0034] Regarding the specific material selection, in some implementations, the substrate material includes any one or a combination of two or more of the following: metal, carbon materials, and ceramic materials. Such combinations may involve the substrate being assembled from multiple components with different materials, or the substrate itself being a composite material of multiple materials, such as a metal-carbon composite material, etc., ensuring optimal thermal conductivity.

[0035] Regarding the more specific choice of materials, in some implementations, the metal includes any one or a combination of two or more of copper, aluminum, and silver.

[0036] In some embodiments, the carbon material includes any one or a combination of two of graphene and thermally conductive carbon fibers.

[0037] Of course, based on the technical teachings and principles given in this invention, the scope of implementation is not limited to the material selection range exemplified above.

[0038] Due to the above characteristics, in some embodiments, the thickness of the three-dimensional graphene composite heat exchanger is less than 400 μm, and preferably in some embodiments, the thickness is less than 200 μm.

[0039] Furthermore, in some embodiments, the thickness of the top and bottom plates of the substrate is typically 20-40 μm. This is to avoid excessive thickness, which would increase thermal resistance, but also to avoid excessive thinness, which would result in a loss of mechanical strength. Of course, the feasible range is not limited to the thickness ranges of the examples above; the optimal range of top and bottom plate thicknesses varies depending on the material or the manufacturing process.

[0040] The foregoing description illustrates the structural features of the three-dimensional graphene composite heat spreader provided by this invention. Corresponding to the aforementioned structural features, a second aspect of this invention also provides a method for fabricating the three-dimensional graphene composite heat spreader. See [link to relevant documentation]. Figure 1 As shown, it includes the following steps:

[0041] S1. Provide three-dimensional graphene having multiple interconnected micropores.

[0042] S2. The three-dimensional graphene is sealed in a plate-shaped substrate to form a three-dimensional graphene composite heat sink.

[0043] The three-dimensional graphene itself contains moisture in its micropores, or the manufacturing method further includes a step of applying moisture to the three-dimensional graphene before sealing and encapsulation.

[0044] In some implementations, in step S1, see Figure 2 As shown, the method for preparing the three-dimensional graphene includes:

[0045] a. Provide a three-dimensional metal skeleton.

[0046] b. Graphene is grown epitaxially in the three-dimensional metal framework; the microstructure of the resulting composite is as follows: Figure 3a As shown.

[0047] c. Remove the three-dimensional metal framework to form the three-dimensional graphene; the microstructure of the formed three-dimensional graphene is as follows: Figure 3b As shown.

[0048] The method for preparing the three-dimensional metal skeleton specifically includes:

[0049] a1. Press the hydrated metal precursor powder into a block.

[0050] a2. The block is subjected to high-temperature dehydration treatment to remove the bound water to form micropores, and then the metal precursor is reduced and annealed to form the three-dimensional metal skeleton.

[0051] Alternatively, a3, provide a high-density sponge and allow the high-density sponge to fully absorb the aqueous solution of the metal precursor.

[0052] a4. Dry the high-density sponge that has absorbed the aqueous solution to remove the free water and retain the bound water.

[0053] a5. The dried high-density sponge is subjected to high-temperature dehydration treatment to remove the bound water in the hydrated metal precursor loaded therein, so as to obtain the precursor template.

[0054] a6. Heat-treat the precursor template to remove the high-density sponge; and perform reduction annealing to obtain the three-dimensional metal skeleton.

[0055] Some existing technologies provide a preparation scheme in which precursor powders such as nickel chloride are laid in a quartz boat, then subjected to high-temperature reduction treatment to form a metal network, and then graphene is grown. However, simply adopting this method of preparing three-dimensional graphene is insufficient to achieve excellent heat dissipation. Graphene grown from metal powder cannot even form interconnected pathways and lacks channels for heat transfer through water molecule vaporization and liquefaction. This invention differs from this one by compressing the powder or by using the adsorption and template effect of high-density sponge, so that the final micropores have a high degree of cross-linking and distribution density, making them very suitable as filling materials in heat spreaders.

[0056] Specifically, in the first preparation method provided by this invention, through compression and dehydration, the water-containing metal halide can form a dense porous structure during the dewatering process. These pores are not only dense but also three-dimensionally cross-linked, providing channels for the subsequent vaporization and flow of water molecules. However, compared to the molding method of high-density sponge, the number of these channels is relatively smaller, and the degree of cross-linking is not as good as that of high-density sponge. Therefore, the heat dissipation effect is slightly weaker than the second preparation method, but it still represents a significant improvement compared to the existing uncompressed preparation method.

[0057] In the second preparation method provided by the present invention, the three-dimensional sponge has a moderate density and is relatively easy to remove in high temperature or organic solution. The sponge itself has a three-dimensional cross-linked structure. After adsorbing the catalyst to grow graphene, the three-dimensional channels are more abundant and the degree of connectivity is higher during the catalyst removal process, which is more conducive to the vaporization and flow of water molecules.

[0058] Of course, the second preparation method is more complicated, which is normal.

[0059] Other existing technologies also provide a technical solution for growing graphene on the surface of nickel foam. Although it is possible to obtain three-dimensional graphene, the density of the graphene formed is too low, and a large amount needs to be stacked. Nickel foam is relatively expensive. More importantly, the amount of channels formed by the grown graphene is insufficient. The three-dimensional graphene network structure formed has no water molecule channels and cannot form an effective heat dissipation path, resulting in poor heat dissipation capacity.

[0060] Therefore, to achieve the preparation of the three-dimensional graphene composite heat spreader of this invention and obtain better heat spreader effect using the existing three-dimensional graphene preparation methods, specific improvements to the relevant preparation process are required.

[0061] Regarding the specific preparation details, in some embodiments, the density of the high-density sponge is 40-60 kg / m³. 3 .

[0062] In some embodiments, the metal precursor is selected from transition metal halides, and more preferably from transition metal chlorides.

[0063] In some embodiments, the metal precursor includes ferric chloride and / or nickel chloride.

[0064] Furthermore, regarding step S2, in some implementations, the hermetically sealed packaging specifically includes:

[0065] A first assembly and a second assembly are provided, wherein at least the first assembly and the second assembly can be joined together to form a closed space.

[0066] The three-dimensional graphene is contained and enclosed in the closed space, and the first assembly and the second assembly are fixedly connected to form the three-dimensional graphene composite heat sink.

[0067] In some implementations, the first assembly and the second assembly are joined together along the thickness direction of the three-dimensional graphene.

[0068] The first assembly and the second assembly described above can be, for example, a combination of a plate with a groove and a cover plate with a flat surface as shown in the following embodiments, or two plates with semi-grooves combined opposite each other, and so on. Various feasible packaging forms can achieve the corresponding technical effects, and are not limited to the specific examples of the present invention.

[0069] As typical application examples of the above technical solutions, the process of the above manufacturing method can be found in [reference needed]. Figure 1 As shown, the specific steps include the following:

[0070] 1) Preparation of three-dimensional catalyst framework: Hydrous ferric chloride / nickel chloride and other metal chlorides (mainly hydrous ferric chloride and hydrous nickel chloride) are directly added to a mold of a certain thickness (this thickness depends on the product customization requirements, for example, if 200mm is made, a corresponding 200mm mold is used), and it is pressed into a block material with a certain density and a thickness of 100-400 micrometers by static pressure (3-20MPa); the prepared block material is rapidly heated (e.g., high temperature 100-300℃, microwave) to quickly remove the bound water and form anhydrous metal chlorides. This process can form a three-dimensional catalyst precursor framework with interconnected channels.

[0071] Alternatively, a saturated nickel chloride solution can be added multiple times to a three-dimensional high-density sponge to allow it to fully absorb the solution. After drying, the dried nickel chloride (containing bound water) sponge can be placed in a microwave oven and microwaved for 1 minute to quickly remove the bound water. Then, heat treatment can be performed to decompose and remove the high-density sponge components, resulting in a porous three-dimensional nickel chloride sheet.

[0072] 2) Preparation of three-dimensional graphene bulk: At a high temperature of 500-1200℃, the prepared three-dimensional metal catalyst precursor framework is placed in an environment with a reducing atmosphere such as hydrogen / carbon monoxide to reduce it to a three-dimensional metal framework at high temperature (using high temperature and reducing gas to reduce metal chloride to metal). Then, using the catalytic effect of the metal, a layer of graphene is deposited on its surface. Then, the metal is removed with dilute acid to form a soft three-dimensional graphene system with interconnected internal channels. Most of the water inside the three-dimensional graphene is removed by low temperature vacuum drying.

[0073] 4) Fix the not-completely-dry 3D graphene in a copper or aluminum plate with internal grooves, then cover it with an ultra-thin copper or aluminum foil, and use a vacuum (0.01-0.1MPa) method to weld the copper or aluminum plate and the copper or aluminum foil together to ensure that the 3D graphene is sealed inside, thus forming a 3D graphene heat sink with graphene as the main heat dissipation material.

[0074] 5) Alternatively, a thick graphene plate can be used as the supporting structure for the three-dimensional graphene vapor chamber, with a density of not less than 2.0 g / cm³. 3 A 200-400 micrometer thick plate is formed by laser etching grooves of about 170-370 micrometers on its surface. Three-dimensional graphene is placed in the grooves, and then a graphene film of about 30 micrometers thick is covered on its surface. The graphene film and the graphene plate are bonded together with graphene oxide slurry. Then, it is heated under certain pressure and temperature for 0.5-20 hours to form a three-dimensional graphene heat sink made entirely of graphene.

[0075] Correspondingly, the embodiments of the present invention also provide the heat conduction application of the three-dimensional graphene composite heat sink provided in any of the above embodiments in any field such as electronic products, aerospace, automobiles, etc., especially heat dissipation applications.

[0076] Based on the specific technical solutions in the above examples, the present invention can achieve the following technical advantages:

[0077] 1) Hydrous metal halides can be pressed into any shape and size. With high temperature or microwave process, the hydrous metal halides melt and dehydrate quickly. After the internal bound water is removed, microchannels can be formed. The microchannels are interconnected. During the later reduction growth of three-dimensional graphene, the microchannels are still preserved.

[0078] 2) While forming microchannels, anhydrous metal halides are also interconnected. Under a reducing atmosphere, they form a cross-linked three-dimensional metal catalyst. The high density allows the graphene to be tightly connected at the atomic size. The chemical vapor deposition method ensures that the grown graphene crystal structure is perfect. Graphene materials with extremely high thermal conductivity can be formed without high-temperature graphitization. Furthermore, due to the tight overlap between graphene sheets, the thermal conductivity is high in all three directions, breaking the problem that the original graphene film only has high thermal conductivity in the horizontal direction and low thermal conductivity in the vertical direction.

[0079] 3) The formation of a heat spreader based on graphene is not limited by thickness. Whether it is 100 micrometers or 300 micrometers thick, its heat dissipation capacity is better than that of traditional synthetic graphite film or graphene oxide thermal conductive film. The ease of processing is not affected by the thickness.

[0080] 4) The all-graphene vapor chamber can maximize the thermal radiation effect of graphene, and its heat dissipation capacity is better than that of conventional vapor chambers on the market.

[0081] 5) The three-dimensional graphene grown from the self-made three-dimensional high-density precursor is different from the traditional method of growing graphene using foam metal. The graphene prepared has the characteristics of high density and interconnected micropores. The density is higher and the graphene grows more compactly, making it more suitable for thermal management applications.

[0082] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0083] Example 1

[0084] This embodiment illustrates the preparation process of a three-dimensional graphene composite heat spreader, as detailed below:

[0085] Nickel chloride hexahydrate is placed in a mold and compacted with a pressure of 10 MPa, with the compaction thickness controlled at 350 micrometers. The compacted nickel chloride hexahydrate block is then placed in a microwave oven and microwaved for 1 minute to quickly remove the bound water, resulting in a porous three-dimensional nickel chloride sheet. A three-dimensional nickel chloride sheet was placed in an atmosphere furnace and heated to 1000°C under an inert protective gas (argon). Then, a small amount of hydrogen was introduced and the temperature was maintained for 10 minutes. Methane gas was then introduced and maintained for 20 minutes. The gas was then turned off and the temperature was lowered to room temperature. The three-dimensional material on which graphene had been grown was removed and immersed in 1 mol / L dilute hydrochloric acid to remove excess metallic nickel. The material was washed thoroughly with water several times and then freeze-dried. A 200-micrometer-thick copper sheet was used, and about 170 micrometers of its thickness was etched off its surface. The freeze-dried graphene was then placed in the etched area. Due to the freeze-drying process, the graphene surface had a significant amount of water adsorbed, about 5-10%. No further heat drying was performed. The three-dimensional graphene with water adsorbed on its surface was directly added to the etched area of ​​the copper sheet. The surface was then covered with copper foil, compacted, and sealed. This process produced a three-dimensional graphene heat spreader containing graphene inside.

[0086] Example 2

[0087] This embodiment illustrates the preparation process of a three-dimensional graphene composite heat spreader, as detailed below:

[0088] A saturated nickel chloride solution was repeatedly added to a 400-micron-thick three-dimensional high-density sponge to allow it to fully absorb the solution. The sponge was then dried. The dried nickel chloride sponge (containing bound water) was placed in a microwave oven and microwaved for 1 minute to quickly remove the bound water, resulting in a porous three-dimensional nickel chloride sheet. A three-dimensional nickel chloride sheet was placed in an atmosphere furnace and heated to 1000℃ under vacuum to remove the organic three-dimensional sponge. Argon gas was then introduced as a protective gas, followed by a trace amount of hydrogen gas, and the temperature was maintained for 10 minutes. Methane gas was then introduced and maintained for 20 minutes. The gas was then turned off, and the temperature was lowered to room temperature. The three-dimensional material on which graphene had been grown was removed and immersed in 1M / L dilute hydrochloric acid to remove excess metallic nickel. The material was then washed thoroughly with water and freeze-dried. A 200-micrometer-thick copper sheet was used, and approximately 170 micrometers of its thickness was etched away from its surface. The freeze-dried graphene was then placed in the etched area. Due to the freeze-drying process, the graphene surface had a significant amount of water adsorbed, approximately 5-10%. Therefore, no further heat drying was performed. The water-adsorbed three-dimensional graphene was directly added to the etched area of ​​the copper sheet. The surface was then covered with copper foil, compacted, and sealed, thus creating a three-dimensional graphene heat sink containing graphene.

[0089] Example 3

[0090] The preparation process of the three-dimensional graphene composite heat spreader in this embodiment is largely the same as that in Example 1, with the only difference being:

[0091] The preparation method is the same as in Example 1, except that the preparation method of the three-dimensional graphene catalyst is different and the catalyst precursor is different. Nickel chloride hexahydrate is replaced with ferric chloride pentahydrate. The rest of the steps are exactly the same as above.

[0092] Example 4

[0093] The preparation process of the three-dimensional graphene composite heat spreader in this embodiment is largely the same as that in Example 1, with the only difference being:

[0094] The preparation method is the same as in Example 1, and the preparation method of three-dimensional graphene is exactly the same. The only difference is the metal material for the outer support. The copper sheet and copper foil are replaced with aluminum sheet and aluminum foil of the same specifications. The rest of the steps are exactly the same as described above.

[0095] Example 5

[0096] The preparation process of the three-dimensional graphene composite heat spreader in this embodiment is largely the same as that in Example 1, with the only difference being:

[0097] The preparation method is the same as in Example 1, and the preparation of three-dimensional graphene is exactly the same, except that the outer supporting substrate is replaced with pure graphene material: a graphene plate with a density of 2.1 g / cm3 and a thickness of 300 micrometers is taken, and a groove 270 micrometers deep is etched on its surface using a laser. A 350-micrometer-thick three-dimensional graphene is placed in the groove, and then a graphene film of about 30 micrometers thick is covered on its surface. A layer of graphene oxide about 10 micrometers thick is coated between the graphene film and the thick graphene plate. Then, the temperature is slowly raised to 1000°C, and the pressure is simultaneously increased to 50 atmospheres. The temperature is maintained for half an hour, and then a three-dimensional graphene heat sink made entirely of graphene is formed. The remaining steps are exactly the same as described above.

[0098] Example 6

[0099] This embodiment illustrates the preparation process of a three-dimensional graphene composite heat spreader, as detailed below:

[0100] Nickel chloride hexahydrate is placed in a mold and compacted with a pressure of 10 MPa, with the compaction thickness controlled at 150 micrometers. The compacted nickel chloride hexahydrate block is then placed in a microwave oven and microwaved for 1 minute to quickly remove the bound water, resulting in a porous three-dimensional nickel chloride sheet. A three-dimensional nickel chloride sheet was placed in an atmosphere furnace and heated to 1000°C under an inert protective gas (argon). Then, a small amount of hydrogen was introduced and the temperature was maintained for 10 minutes. Methane gas was then introduced and maintained for 20 minutes. The gas was then turned off and the temperature was lowered to room temperature. The three-dimensional material on which graphene had been grown was removed and immersed in 1 M / L dilute hydrochloric acid to remove excess metallic nickel. The material was washed thoroughly with water several times and then freeze-dried. A 100-micrometer-thick copper sheet was used, and about 80 micrometers of its thickness was etched off its surface. The freeze-dried graphene was then placed in the etched area. Due to the freeze-drying process, the graphene surface had a significant amount of water adsorbed, about 5-10%. No further heat drying was performed. The three-dimensional graphene with water adsorbed on its surface was directly added to the etched area of ​​the copper sheet. The surface was then covered with copper foil, compacted, and sealed. This process produced a three-dimensional graphene heat spreader containing graphene inside.

[0101] Comparative Example 1

[0102] The preparation process of the three-dimensional graphene composite heat spreader in this comparative example is largely the same as that in Example 1, with the main difference being:

[0103] The preparation method is the same as in Example 1, and the preparation method of three-dimensional graphene is exactly the same. The only difference is that nickel foam is used as the graphene growth framework. The thickness of the nickel foam is 1.5 mm. Since the density of nickel foam is low, the amount of graphene grown is limited. Two layers of nickel foam are stacked together and then pressed into the groove.

[0104] Comparative Example 2

[0105] This comparative example provides a commercially available 300-micron thick copper vapor chamber.

[0106] Test case

[0107] Heat dissipation effect test: Since the graphene vapor chamber relies on the phase change of water molecules for heat dissipation, the introduction of graphene can transfer heat to water molecules more quickly. Therefore, directly measuring thermal conductivity would be difficult. This test example directly uses a heat dissipation effect test, with the following setup: Figure 4a and Figure 4b As shown.

[0108] Equal-sized heat spreaders were prepared by constant-temperature heating. Two thermocouples were then placed at the same position on the heat spreaders, and the temperatures of the thermocouples were measured. The average value was plotted as a curve. The lower the temperature after stabilization, the better the heat dissipation effect.

[0109] The final measured equilibrium temperature curve test results for some of the embodiments and comparative examples are as follows: Figure 5 As shown.

[0110] By comparison, it can be found that the heat dissipation performance of the three-dimensional graphene composite heat exchanger in the various embodiments provided by the present invention is significantly stronger than that of the commercially available traditional copper-based heat exchanger in Comparative Example 2; moreover, compared with the existing three-dimensional graphene preparation method in Comparative Example 1, the heat dissipation performance of the heat exchanger prepared by the unique preparation method used in the embodiments is significantly better.

[0111] Furthermore, a comparison between Example 1 and Example 5 reveals that using pure graphene as the substrate can further improve heat dissipation performance compared to a metal substrate. In addition, a comparison between Example 1 and Example 2 shows that the heat dissipation performance of the vapor chamber formed by using the high-density sponge adsorption method to prepare three-dimensional graphene is better, which is due to the effect of higher micropore density and stronger connectivity.

[0112] Based on the above embodiments and comparative examples, it can be clearly seen that the heat dissipation capacity of the three-dimensional graphene composite heat dissipation plate provided by the embodiments of the present invention is not limited by thickness. It can still maintain excellent heat dissipation capacity at different thicknesses, especially at thicknesses below 400μm, and the ease of processing is also not affected by thickness. In addition, the three-dimensional graphene composite heat dissipation plate provided by the present invention can also exert the thermal radiation effect of graphene, and its heat dissipation capacity is further superior to that of conventional heat dissipation plates.

[0113] Furthermore, the three-dimensional graphene composite heat spreader preparation method provided in this embodiment of the invention produces three-dimensional graphene with high density and interconnected micropores. This results in higher density, more compact graphene growth, and greater suitability for thermal management applications.

[0114] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for fabricating a three-dimensional graphene composite heat spreader, characterized in that, include: A three-dimensional graphene is provided, the three-dimensional graphene having multiple interconnected micropores, and the preparation method of the three-dimensional graphene includes: Provide a three-dimensional metal skeleton; Graphene is grown by vapor phase epitaxy in the three-dimensional metal framework. The three-dimensional metal framework is removed to form the three-dimensional graphene; The method for preparing the three-dimensional metal skeleton specifically includes: Hydrated metal precursor powder is pressed into bulk material; The block is subjected to high-temperature dehydration treatment to remove the bound water and form micropores, and then the metal precursor is reduced and annealed to form the three-dimensional metal skeleton. Alternatively, a high-density sponge is provided, and the high-density sponge is allowed to fully absorb the aqueous solution of the metal precursor; The high-density sponge that has absorbed the aqueous solution is dried to remove the free water while retaining the bound water; The dried high-density sponge is subjected to high-temperature dehydration treatment to remove the bound water in the hydrated metal precursor loaded therein, thereby obtaining a precursor template. The precursor template is heat-treated to remove the high-density sponge; and a reduction annealing process is performed to obtain the three-dimensional metal skeleton. The three-dimensional graphene is sealed and encapsulated in a plate-shaped substrate to form a three-dimensional graphene composite heat sink. The three-dimensional graphene itself contains moisture in its micropores, or the manufacturing method further includes a step of applying moisture to the three-dimensional graphene before sealing and encapsulation.

2. The manufacturing method according to claim 1, characterized in that, The density of the high-density sponge is 40-60 kg / m³. 3 The metal precursor is selected from transition metal halides, and the metal precursor includes ferric chloride and / or nickel chloride.

3. The manufacturing method according to claim 1, characterized in that, The sealed packaging specifically includes: A first assembly and a second assembly are provided, wherein at least the first assembly and the second assembly can be joined together to form a closed space; The three-dimensional graphene is contained and enclosed in the closed space, and the first assembly and the second assembly are fixedly connected to form the three-dimensional graphene composite heat sink. The first assembly and the second assembly are spliced ​​together along the thickness direction of the three-dimensional graphene.

4. A three-dimensional graphene composite heat spreader prepared by the method according to any one of claims 1-3, characterized in that, include: The matrix and the three-dimensional graphene enclosed within the matrix; The three-dimensional graphene has multiple interconnected micropores, and the micropores contain water.

5. The three-dimensional graphene composite heat spreader according to claim 4, characterized in that, The surface water content in the three-dimensional graphene is 5-10%.

6. The three-dimensional graphene composite heat spreader according to claim 4, characterized in that, The microchannels include multiple main channels and secondary channels; The multiple main channels are interconnected to form a main channel network; the multiple secondary channels are at least connected to the adjacent main channels; The main network of pores extends through both opposite sides of the three-dimensional graphene.

7. The three-dimensional graphene composite heat spreader according to claim 4, characterized in that, The substrate material includes any one or a combination of two or more of the following: metal, carbon materials, and ceramic materials.

8. The three-dimensional graphene composite heat spreader according to claim 7, characterized in that, The metal includes any one or a combination of two or more of copper, aluminum, and silver; And / or, the carbon material includes any one or a combination of two of graphene and thermally conductive carbon fibers.

9. The three-dimensional graphene composite heat spreader according to claim 4, characterized in that, The thickness of the three-dimensional graphene composite heat exchanger is less than 400 μm.

10. The three-dimensional graphene composite heat spreader according to claim 4, characterized in that, The thickness of the top and bottom plates of the substrate is 20-40 μm.

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